A Moon of Saturn Has a Sea, Scientists Say(nytimes.com) |
A Moon of Saturn Has a Sea, Scientists Say(nytimes.com) |
The challenges are to make sure that the interesting particles would not break apart, to take precautions that any alien life would not infect Earth, and to fit it into the $500 million budget of one of NASA’s lower-cost planetary missions.
It frames it all beautifully. Engineering feats solving problems you don't quite understand. Sci fi potential. Budgetary drudgery.
One of the more interesting stories about microbes in space is that some survived on the moon for almost three years inside a camera [3]. It is not 100% certain that the microbes cultured were not from later contamination, but I know from working with them that microbes are really tough and I can believe that they could have survived!
[0] http://users.tpg.com.au/horsts/transpermia.html
[1] http://www.ncbi.nlm.nih.gov/pubmed/19854226
[2] http://en.wikipedia.org/wiki/Panspermia
[3] http://en.wikipedia.org/wiki/Reports_of_Streptococcus_mitis_...
There is really no way of proving transpermia - even if we to travel to Enceladus and found microbial life there how would we ever prove how it got there.
Plus NASA's actual release about the sea: http://science.nasa.gov/science-news/science-at-nasa/2014/03...
The challenges are to make sure that the interesting particles would not break apart, to take precautions that any alien life would not infect Earth, and to fit it into the $500 million budget of one of NASA’s lower-cost planetary missions."
Why bring it back to earth? Wouldn't it be safer & less expensive to return it to ISS instead, (or is that what's implied) ?
Didn't know the carbon & nitrogen part of the story, read the article thinking only 1 thing: "when are you going to mention Europa".
Dr. McKay, who was not involved with gravity measurements, noted that only Enceladus was known to possess the four essential ingredients for life, at least as it exists on Earth: liquid water, energy, carbon and nitrogen.
“I would say it’s our best bet,” he said.
Mars has a dearth of nitrogen, found in amino acids and proteins, and the surface today is dry and cold. Europa, which also possesses an under-ice ocean, may have all of the ingredients, but that has not been confirmed.
Amusingly, I have Europa as a colony in a comic I write. In mentioning this elsewhere just now, a physicist has suggested this resource to me: http://en.wikipedia.org/wiki/Solar_System_in_fiction#Comics_...
I shall have to learn yet more about our solar system so I can make up dumb bs for humor's sake.
(Not that I expect anyone here to really care. I am just cracking up over this.)
They found the gravity was weaker.. but it should actually have been weaker. So is it weaker or stronger?
On the other hand I didn’t know Enceladus until today. (I fist thought the story was about Titan.)
My preferred title for the HN submission would be “Enceladus, A Moon of Saturn, Has a Sea” or “A Moon of Saturn [Enceladus] Has a Sea”.
Doesn't quite have the same ring to it.
No, that would involve a very complicated and expensive breaking maneuver to slow down the spacecraft, not to mention getting in exactly the right orbit to rendezvous with the ISS. It's much, much easier to just the payload sturdy enough to survive atmospheric entry and a crash landing.
(Sorry, normally I wouldn't nitpick spelling when the meaning is clear, it was just a funny error!)
I know, I know, budgets. It'll 'never' happen.
But what if we just send a nano-factory with its own assembly/disassembly abilities? Feasible, 5 - 10 years on from now?
Well anyway, the point is: why bring it back, really? Just send more machines to do better jobs in space.
Regarding planetary contamination, with the amount of meteorites hitting ocean I do not think we have anything to worry about.
The amount of oxygen in the atmosphere helps a lot. The onset of photosynthesis caused a mass extinction ~two billion years ago.
https://en.wikipedia.org/wiki/Great_Oxygenation_Event
I love that name. It sounds like some kind of a party.
But regarding your last sentence: I'm not very fond of that risk analysis. Potentially introducing an alien aquatic micro-organism (that's what we hope to bring back, remember) into earth's system... No competition, paradise compared to its hostile home. No meteorite has ever been shown to carry life, but into this case we intend to deliberately introduce it, either controlled or uncontrolled.
NASA can bill me for the extra cost for taking it to ISS instead of earth's surface.
I'm surprised that we aren't equally worried about contaminating Enceladus with terran microbes.
I don't think that would be a real risk. Earth life has spent billions of years both adapting and adapting to the environment to make it the best growing medium and even then it exists in exclusive bands. For example, put a polar bear in the desert or a fresh water fish in salt water. It is more likely that we would have to take extreme care not to kill any lifeforms we brought back than to worry about them killing us.
- rabbits/cane toads in Australia [0][1]
- Japanese knotweed [2]
- Tumbleweed (yep, not as native as Hollywood suggests) [3]
- Algae [4]
... and the list goes on and on, here's a top-100:
http://en.wikipedia.org/wiki/List_of_the_world%27s_100_worst...
[0] http://www.youtube.com/watch?v=pgPhn4tYxJQ
[1] http://en.wikipedia.org/wiki/Cane_toads_in_Australia
[2] http://www.environment-agency.gov.uk/homeandleisure/wildlife...
* There's a depression -> gravity weaker.
* Less of a difference than expected from the depression size -> something denser
* Water is denser than ice, and in a known relation -> size/volume of lake."We determined the quadrupole gravity field of Enceladus and its hemispherical asymmetry using Doppler data from three spacecraft flybys. Our results indicate the presence of a negative mass anomaly in the south-polar region, largely compensated by a positive subsurface anomaly compatible with the presence of a regional subsurface sea at depths of 30 to 40 kilometers and extending up to south latitudes of about 50°.
And a little more on methodology, from the full article:
"The design of the Cassini spacecraft does not allow radio tracking from Earth during remote-sensing observations. Therefore, only 3 of the 19 flybys of Enceladus completed so far have been used for gravity measurements. In these close encounters, the spacecraft was continuously tracked from ground antennas while flying within 100 km of the moon’s surface, twice above the southern hemisphere (in the flybys labeled E9 and E19) and once over the northern hemisphere (E12). We determined Enceladus’ quadrupole gravity field and degree-3 zonal harmonic coefficient J3 from measurements of spacecraft range-rate.
And further detail on the effects modeled:
"Microwave links between the onboard transponder and ground stations of NASA’s Deep Space Network enabled precise measurements of the spacecraft range-rate. In addition to gravitational forces, our analysis accounts for the main nongravitational accelerations, most notably neutral particle drag exerted by the substantial gas plume formed by the jets of the south-polar region. Flying by the moon at latitudes below –70°, the spacecraft interacts with the plume at distances of up to 500 km from Enceladus’ surface..."
Amazing results. They're flying ~100 km from the moon's surface, while at a distance of 1.3 billion km. And getting very accurate velocities due to the mighty Doppler effect.
In the board game Evo, your odds of success in combat are determined by comparing the number of horns your species has to the number the other species has.
Specifically, the following circumstances are considered:
- Each species has the same number of horns as the other
- One species has one more horn than the other
- One species has two or more more horns than the other
It's always fun to explain that part.
In the current context, "weakerer" isn't a word, but it would be quite normal to say "even weaker".
A life form which evolved in a (relatively) low-energy environment (low temperature, low light level, lower pressure) is more in hell than in a paradise. Earth organism evolved to make the best of available resources on Earth, be it energy or materials; the organism would be teared apart in no-time.
That is, unless it is a highly intelligent and evolved life form with big environment alteration capacities, but then it might already be a problem, just one we aren't aware of.
Get FAR, RSS, Deadly Rentry, put your space station somewhere around 50 degrees inclination, then try it with suitably small probe. The Stardust spacecraft was 300kg; the sample return capsule was 46kg and reentered at nearly 13km/s.
Just one full small kerbal RCS tank puts you at 250kg, so you'll need to nearly empty that just for starters...
Because of the technical simplicity and sensitivity of looking for DNA, any probe sent to any planet or moon would look for DNA first, basically assuming transpermia is true.
[0] http://en.wikipedia.org/wiki/Lost_City_(hydrothermal_field)
What is this frequency, exactly? My impression was that all planets are constantly bombarded with rocks from space (not from other planets), but that it would be extremely surprising for a rock to e.g. leave Earth and end up on Mercury.
(that is, the probe as whole can still orbit the sun in the same direction as the planet, it just needs to do it slower.
(ducks)